Muscular echovariation: a new biomarker in amyotrophic lateral sclerosis

The purpose is to assess the characteristics of echovariation in amyotrophic lateral sclerosis (ALS) compared with other MUS parameters. Twenty-six ALS patients (8 women, mean age 58.9 years, SD 12.02 yr) and 26 healthy controls (17 women; mean age 59.6 years, SD 6.41 yr) were included in this observational study. They underwent bilateral and transverse ultrasound of the biceps/brachialis, forearm flexor group, quadriceps femoris and tibialis anterior. Muscular thickness, echointensity and echovariation were analyzed. Muscles affected by ALS showed increased echointensity, decrease in thickness, and decrease echovariation. Echovariation in all muscles but quadriceps femoris, strongly correlated with muscle strength (explained variance between 21.8% in the biceps/brachialis and 37.5% in tibialis anterior) and the ALSFRS-R score (explained variance between 26% in the biceps/brachialis and 36.7% in the forearm flexor group). Echovariation is an easy to obtain QMUS parameter that could distinguish ALS from healthy controls more accurately than previous described biomarkers.